Dual Gauge Turntables

[Compound2632]

2 minutes ago, jim.snowdon said:

The original decision to adopt broad gauge was sound enough at the time, but what could be argued as technical excellence was swamped by the sheer quantity of standard gauge track that was built. Shades of Betamax and VHS many decades later.

 

From the beginning, the broad gauge was technically flawed both in concept and implementation. However, that only became apparent with the passage of time. Brunel made a brave attempt to re-think the concept of the long-distance railway from a standpoint outside the Stephenson circle; as much by luck as by judgement the Stephensonian (or perhaps one should say Lockean) way turned out to be nearer the optimum solution. 

[jim.snowdon]

1 minute ago, Compound2632 said:

 

From the beginning, the broad gauge was technically flawed both in concept and implementation. However, that only became apparent with the passage of time. Brunel made a brave attempt to re-think the concept of the long-distance railway from a standpoint outside the Stephenson circle; as much by luck as by judgement the Stephensonian (or perhaps one should say Lockean) way turned out to be nearer the optimum solution. 

Interesting. How would you describe the broad gauge as technically flawed? The engineering all worked, and as far as I have seen, worked quite well. Its real weakness was at the interfaces with the other standard gauge railways (of which there were rather fewer in the 1830s and 40s.

 

[The Stationmaster]

22 minutes ago, Compound2632 said:

 

I can see that, and it does make more sense that the layout would be changed as part of the conversion rather than later. Presumably this entailed relaying most of the station area with transverse-sleepered track, even though the plain line remained baulk road - assuming it was in the first place?

But the evidence is that did not happen.  All the mixed gauge conversions I can find were either change to the broad gauge in order to accommodate narrow gauge trains over certain routes/part of those routes or, as on part of the Cornwall Railway, change to a narrow gauge line to enable it to also handle broad gauge trains.   Thus - for example - although the mixed gauge was extended to Plymouth Millbay that was almsot ceratinly only for freight traffic and Millbay station - as photos illustrate - was never mixed gauge  going straight from broad to narrow gauge by the usual method of altering the baiulk road.

 

Sleepered mixed gauge track  did exist in a few places but seems to have been wholly on plain line, all pointwork that I can find pictures of, including some which survived as narrow gauge line well into the 1920s on one branch , was baulk road.  And baulk road plain line was actually easier and quicker to narrow than sleepered track.

 

The often overlooked major gauge conversion of the South Wales route in May 1972 saw the abolition of 265 miles of broad gauge and only 41 miles of mixed gauge (plus the preparatory conversion of c.25 miles of broad gauge from Didcot to Swindon to mixed gauge, which remained until 1892).  The more readily remembered conversion of the West of England route in May 1892 saw the abolition of the final 171 miles of broad gauge and the final 252 miles of mixed gauge but only 60 miles of that mixed gauge was west of Exeter and 25 miles of that was in Cornwall (see earlier comment).  There is clear evidence in both the 1872 and 1892 conversions that major stations were converted directly from broad gauge to narrow,  all the conversions to mixed or narrow gauge between 1872 and 1892 were on a route basis.  Narrow gauge mileage at the end of 1872 was 977 and by December 1875 had increased to 1402 while GWR purely broad gauge mileage at the end of 1875 was a mere 6 miles with only 122 miles of mixed gauge.  Within a year the amalgamations in the West of England had increased the purely broad gauge mileage to 268 and the mixed had increased to 273.

 

Following a minor increase in the next couple of years mixed gauge reached its post 1876 maximum of 276 miles and had declined to 252 miles by the end of 1891.  In other words the mixed gauge total did not increase after 1876 indicating - if nothing else - that no changes were made to facilitate ultimate gauge narrowing. (incidentally short distances through or near major stations are identified separately in the source details I have used).  Between the end of 1872 and the end of 1891and GWR purely narrow gauge mileage increased from 977 to 1982

[Compound2632]

56 minutes ago, jim.snowdon said:

Interesting. How would you describe the broad gauge as technically flawed? The engineering all worked, and as far as I have seen, worked quite well. Its real weakness was at the interfaces with the other standard gauge railways (of which there were rather fewer in the 1830s and 40s.

 

 

See my post previous to the one you are quoting:

Also tied in with this was the general misconception that a low centre of gravity (relative to the gauge) was essential. In fact, for a low centre of gravity, the transverse forces on the rails are greater relative to the vertical forces than for a high centre of gravity but the rails are much better at withstanding vertical than transverse forces.

 

I'd settle for calling the broad gauge a brilliant experiment but ultimately flawed technically and economically. But there's no denying it looks good! Brunel's real genius was as a civil engineer; perhaps his bridge of the Thames at Maidenhead is the greatest witness to this.

 

Edited September 27, 2021 by Compound2632

[kevinlms]

2 hours ago, jim.snowdon said:

Interesting. How would you describe the broad gauge as technically flawed? The engineering all worked, and as far as I have seen, worked quite well. Its real weakness was at the interfaces with the other standard gauge railways (of which there were rather fewer in the 1830s and 40s.

 

Why would anyone want a change of gauge location? Operationally they were nothing but a PITA and best avoided. What is telling is that nowhere outside the GWR area went for Broad Gauge.

 

Things could have been entirely different if the Great Northern or Midland Railway (just picking large contemporary railways - nothing sinister) had adopted Brunel's gauge and standards.

 

Even the Midland, who met at the largest number of change of gauge locations and purchased the Bristol and Gloucester Railway (7ft gauge) weren't interested in adopting the broad gauge.

[kevinlms]

1 hour ago, Compound2632 said:

 

See my post previous to the one you are quoting:

Also tied in with this was the general misconception that a low centre of gravity (relative to the gauge) was essential. In fact, for a low centre of gravity, the transverse forces on the rails are greater relative to the vertical forces than for a high centre of gravity but the rails are much better at withstanding vertical than transverse forces.

 

I'd settle for calling the broad gauge a brilliant experiment but ultimately flawed technically and economically. But there's no denying it looks good! Brunel's real genius was as a civil engineer; perhaps his bridge of the Thames at Maidenhead is the greatest witness to this.

 

To be fair, the low centre of gravity idea had to be built and proven to be false. Lots of pioneer ideas by others failed too. The Liverpool and Manchester line was built on the basis that the up & down rails were standard gauge distance apart, so that larger loads could be carried down the centre. Not sure that it ever happened.

 

[Compound2632]

50 minutes ago, kevinlms said:

To be fair, the low centre of gravity idea had to be built and proven to be false. 

 

Yes, I called it a general misconception, by no means specific to Brunel.

Edited September 27, 2021 by Compound2632

[John Hubbard]

On 26/09/2021 at 12:14, Compound2632 said:

 

Here's the Ordnance Survey's impression of Moretonhampstead in 1885, when the line was still broad gauge; the goods shed road runs directly into the passenger line: https://maps.nls.uk/view/136635962.

 

By 1904, the loop has been lengthened, with a crossover beyond the train shed, and the goods shed line runs into the loop, via a plain crossing over the passenger line: https://maps.nls.uk/view/106004264; on the other hand, the shed road, which had been connected to the passenger line via a crossing (probably a slip) over the loop, is now connected only to the loop. Plus an extra siding. There are presumably some traps that were beneath the surveyor's notice.

 

As the gauge conversion was done over a weekend in 1892, it seems unlikely to me that the layout was changed then; I suppose it must have been improvement work at some point in the following decade.

 

The small turntable in front of the engine shed had been removed by 1936: https://maps.nls.uk/view/106004267.

 

I can't resist posting this very nice photo:

 

 

[Public Domain, https://commons.wikimedia.org/w/index.php?curid=15282237]

 

The Wikipedia caption says c. 1909 but not before 1905 but my understanding of Great Western carriage liveries tells me that 1909 is the earliest possible date and it is perhaps several years after - the brown or maybe lake carriages have been in service for a good while, given that their white roofs have gone to as dark a grey as those of the two carriages still in pre-1908 livery; their varnish has dulled a bit, too. (I read that brown started to be applied in late summer / early autumn 1908, with some carriages still being turned out in chocolate and cream to the end of the year; the photo is clearly high summer; if it was 1908, the brown carriages would have fresh white roofs! )

It's a great picture and very inspirational for perhaps hundreds of GWR BLT's over the years, and I like the reasoning regarding the date too, it makes a lot of sense.

WRT track, my fiction will be that this is one of the few lines that had dual gauge track, at least for a period (my train-set my rules ).  As my time frame will be from ~1860 to ~1899, I think I can keep the TT in front of the Engine shed and include the Good shed running in to a loop, however I will take on board the need for some catch points.

Now where is that soldering iron, BG rail, and timber?

[Compound2632]

3 hours ago, John Hubbard said:

It's a great picture

 

... I fixated on the carriages but, looking again, I see it is baulk track, per Mike @The Stationmaster's post above.

[jim.snowdon]

7 hours ago, Compound2632 said:

Also tied in with this was the general misconception that a low centre of gravity (relative to the gauge) was essential. In fact, for a low centre of gravity, the transverse forces on the rails are greater relative to the vertical forces than for a high centre of gravity but the rails are much better at withstanding vertical than transverse forces.

True, although with what we know today about wheel/rail forces, unknown then, the lateral forces on curves can be very significant, as can the effects of centrifugal force when running at elevated rates of cant deficiency with both conventional and tilting trains. That, however, is another subject altogether.

 

 

[Compound2632]

Re. Moretonhampstead, there's a very nice 2 mm finescale version by Pete Warren in the latest Model Railway Journal, though set not in the BG or immediate post-conversion period but the classic GWR BLT never-never-land of the late 30s. Serendipitously, I was leafing yesterday through a pile of old issues of Railway Modeller recovered from my parents' loft and came upon a Wolverhampton MRC model, described but not built by Tony Wright (Feb 1987). That gives a track diagram for 1913 - re-drawn in characteristic RM house style - which, to get vaguely back on topic, shows a pit - inspection or ash? - in the position outside the engine shed formerly occupied by the turntable.

[The Stationmaster]

1 hour ago, Compound2632 said:

Re. Moretonhampstead, there's a very nice 2 mm finescale version by Pete Warren in the latest Model Railway Journal, though set not in the BG or immediate post-conversion period but the classic GWR BLT never-never-land of the late 30s. Serendipitously, I was leafing yesterday through a pile of old issues of Railway Modeller recovered from my parents' loft and came upon a Wolverhampton MRC model, described but not built by Tony Wright (Feb 1987). That gives a track diagram for 1913 - re-drawn in characteristic RM house style - which, to get vaguely back on topic, shows a pit - inspection or ash? - in the position outside the engine shed formerly occupied by the turntable.

The depth of a pit will normally indicate its intended purpose as ash pits were deeper than preparation pits.

[Compound2632]

5 minutes ago, The Stationmaster said:

The depth of a pit will normally indicate its intended purpose as ash pits were deeper than preparation pits.

 

Well, depth not indicated on the RM plan! I suppose that it's more likely an ash pit, being outdoors near the coaling stage; perhaps there's a preparation pit inside the shed. Though that would have been awkward to convert from BG! It's unclear what Pete Warren thinks - if it is an ash pit, someone's been busy barrowing the ash away; there's apparently no heap at the lineside.

[melmerby]

Dundee was lucky in the early days, the Dundee & Newtyle & associated lines were 4' 6½", the Perth & Dundee was 4' 8½" and the Dundee & Arbroath was 5' 6"

Edited October 1, 2021 by melmerby

[Forward!]

So I've just looked at the earliest large-scale map I can find for Westcote Park Shed(s?) and interestingly, it looks like they had both arrangements of turntable! These are a couple of screenshots.

 

Haven't really got enough time today to look at the Crossrail Archaeology stuff, but here's the link if anyone wants to have a look for some evidence: https://learninglegacy.crossrail.co.uk/documents/archaeology-archive-westbourne-park-and-royal-oak-portal/

 

Hope that's useful.

 

Will

 

 

 

 

 

 

Edited October 8, 2021 by Forward!

[The Stationmaster]

On 01/10/2021 at 16:28, Compound2632 said:

 

Well, depth not indicated on the RM plan! I suppose that it's more likely an ash pit, being outdoors near the coaling stage; perhaps there's a preparation pit inside the shed. Though that would have been awkward to convert from BG! It's unclear what Pete Warren thinks - if it is an ash pit, someone's been busy barrowing the ash away; there's apparently no heap at the lineside.

If it's near the coal stage it is more likely to be an ashpit although in saying that I'm assuming that early practice was similar to the way things were in the Churchward era (and later) depots.